Feature 2 | HIGH-SPEED DIESEL ENGINES
through the combination of advanced emissions reduction technology and the use of ultra-low sulphur diesel fuel. Against the backcloth of strong demand
for the Cat 3500 family of high-speed engines and a tightening environmental regime in the USA and Europe, Caterpillar followed-up the 2005 introduction of the higher-rated 3500C-HD (high-displace- ment) family with a new clutch of 3500C models offering lower emissions and a narrower engine profile. US EPA Tier 2 emissions-compliant
3500C engines have been released in 8-, 12-, and 16-cylinder models covering the power range from 578kW to 2525kW, and suited to the propulsion needs of inland vessels, workboats, patrol craſt, tugs, fast ferries, coastal traders, and yachts, and including versions for marine auxiliary duties. Models are offered at 1200rev/min, 1600rev/min, and 1800rev/min running speeds, in ratings from A to D, to match specific application criteria. New hardware and soſtware has led
to advanced ratings with competitive fuel consumption, while promising long engine life and reduced maintenance costs, compared to most other engines in the same class. Te new ratings have special signifi-
cance for the river towage and harbour tug market, by resulting in increased bollard pull while allowing for compact enginerooms. Reserve power capability is such as to ensure quick response and acceleration when required. In addition, new ratings have been
developed to work with 600/690V 60Hz diesel-electric propulsion as well as 400/440V 60Hz marine auxiliary gensets. For these purposes, output ratings have been increased by as much as 25% to 1700ekW in the case of the 3512C-HD, and by 23% to 2250ekW for the 3516C-HD. Meanwhile, Scania’s latest 121-type
engine has been up-rated to a maximum output of 550kW for so-called ‘patrol short’ operations. For ‘patrol long’ service, the engine is also available at 405kW or 460kW ratings. Te new version features dual charge-coolers to secure sufficient intake air cooling with the high boost pressures involved. Te engine incorpo- rates Scania EMS, an in-house developed engine management system that gives a high degree of flexibility to tailor engine
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performance to individual customer applications. It complies with US EPA Tier 2 emission requirements.
Innovation Te combination of additional power and highly competitive fuel consumption in the 3500C-HD engines is attributed to the adoption of Caterpillar ACERT technol- ogy components. Hardware incorporated includes optimised injector spray angles and a combustion crater, high-efficiency turbochargers, A3 electronic control unit (ECU), drilled conrods, and high-flow piston cooling jets. For the 16-cylinder high power ratings,
a modular pulse exhaust manifold combines with a wastegate to optimise turbocharger efficiency. The manifold conserves exhaust pulse energy for maximum thermal efficiency at the engine turbochargers. Te wastegate provides acceleration at low- and medium-speeds. Te company’s high-speed offering has
also been strengthened by the introduc- tion of ACERT versions of the C18 and C32 marine engines. The electronically-controlled C18
ACERT is a six-cylinder, in-line diesel, offering a long-term emissions solution while giving the requisite power and maintaining the same weight and package size as the previous C18 propulsion engine. It embodies the building blocks of the proprietary ACERT technology such
as high-pressure fuel injection, electronic controls, efficient combustion, and aſter- cooling to keep emissions and smoke levels to a minimum, and compliant with EPA Tier 2 stipulations. Te engine is available in eight ratings,
spanning the 339kW-651kW band and crankshaft speeds from 1800rev/ min to 2200rev/min, and is targeted at tug, offshore service vessel, patrol craſt, passenger vessel, fishing boat, and other displacement hull commercial applications. In its auxiliary version, the new Cat C18
ACERT marine genset balances power density and fuel efficiency with EPA Tier 2 emissions compliance to match 50Hz (1500rev/min) and 60Hz (1800rev/min) generators. Te C32 ACERT engine for commercial
marine propulsion and genset use is of a mass suited to the requirements of craſt and vessels where the lower weight of the engine and the vessel as a whole can be directly translated into fuel savings and increased revenue potential. The high displacement and high torque delivers improved acceleration in comparison with the design’s predecessors, the Cat C30, 3412D, and 3412E engines. Ten ratings cover propulsion applica-
tions from 660bhp to 1600bhp (approxi- mately 490kW-1200kW), at running speeds in the 1600rev/min-2300rev/min range, while six further ratings serve the
The Caterpillar C32 ACERT delivers more power than the 3412E and C32 Tier I engines, but is similar in size.
Ship & Boat International May/June 2008
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